8 #include <unordered_set>
15 #include "service-listener.h"
16 #include "service-constants.h"
18 #include "dinit-log.h"
21 * This header defines service_record, a data record maintaining information about a service,
22 * and service_set, a set of interdependent service records. It also defines some associated
23 * types and exceptions.
27 * Services have both a current state and a desired state. The desired state can be
28 * either STARTED or STOPPED. The current state can also be STARTING or STOPPING.
29 * A service can be "pinned" in either the STARTED or STOPPED states to prevent it
30 * from leaving that state until it is unpinned.
32 * The total state is a combination of the two, current and desired:
33 * STOPPED/STOPPED : stopped and will remain stopped
34 * STOPPED/STARTED : stopped (pinned), must be unpinned to start
35 * STARTING/STARTED : starting, but not yet started. Dependencies may also be starting.
36 * STARTING/STOPPED : as above, but the service will be stopped again as soon as it has
38 * STARTED/STARTED : running and will continue running.
39 * STARTED/STOPPED : started (pinned), must be unpinned to stop
40 * STOPPING/STOPPED : stopping and will stop. Dependents may be stopping.
41 * STOPPING/STARTED : as above, but the service will be re-started again once it stops.
43 * A scripted service is in the STARTING/STOPPING states during the script execution.
44 * A process service is in the STOPPING state when it has been signalled to stop, and is
45 * in the STARTING state when waiting for dependencies to start or for the exec() call in
46 * the forked child to complete and return a status.
48 * Acquisition/release:
50 * Each service has a dependent-count ("required_by"). This starts at 0, adds 1 if the
51 * service has explicitly been started (i.e. "start_explicit" is true), and adds 1 for
52 * each dependent service which is not STOPPED (including dependents with a soft dependency).
53 * When required_by transitions to 0, the service is stopped (unless it is pinned). When
54 * require_by transitions from 0, the service is started (unless pinned).
56 * So, in general, the dependent-count determines the desired state (STARTED if the count
57 * is greater than 0, otherwise STOPPED). However, a service can be issued a stop-and-take
58 * down order (via `stop(true)'); this will first stop dependent services, which may restart
59 * and cancel the stop of the former service. Finally, a service can be force-stopped, which
60 * means that its stop process cannot be cancelled (though it may still be put in a desired
61 * state of STARTED, meaning it will start immediately upon stopping).
65 * A service may be "pinned" in either STARTED or STOPPED states (or even both). Once it
66 * reaches a pinned state, a service will not leave that state, though its desired state
67 * may still be set. (Note that pinning prevents, but never causes, state transition).
69 * The priority of the different state deciders is:
72 * - desired state (which is manipulated by require/release operations)
74 * So a forced stop cannot occur until the service is not pinned started, for instance.
76 * Two-phase transition
77 * --------------------
78 * Transition between states occurs in two phases: propagation and execution. In both phases
79 * a linked-list queue is used to keep track of which services need processing; this avoids
80 * recursion (which would be of unknown depth and therefore liable to stack overflow).
82 * In the propagation phase, acquisition/release messages are processed, and desired state may be
83 * altered accordingly. Start and stop requests are also propagated in this phase. The state may
84 * be set to STARTING or STOPPING to reflect the desired state, but will never be set to STARTED
85 * or STOPPED (that happens in the execution phase).
87 * Propagation variables:
88 * prop_acquire: the service has transitioned to an acquired state and must issue an acquire
90 * prop_release: the service has transitioned to a released state and must issue a release on
93 * prop_start: the service should start
94 * prop_stop: the service should stop
96 * Note that "prop_acquire"/"prop_release" form a pair which cannot both be set at the same time
97 * which is enforced via explicit checks. For "prop_start"/"prop_stop" this occurs implicitly.
99 * In the execution phase, actions are taken to achieve the desired state. Actual state may
100 * transition according to the current and desired states. Processes can be sent signals, etc
101 * in order to stop them. A process can restart if it stops, but it does so by raising prop_start
102 * which needs to be processed in a second transition phase. Seeing as starting never causes
103 * another process to stop, the transition-execute-transition cycle always ends at the 2nd
104 * transition stage, at the latest.
107 struct onstart_flags_t {
108 bool rw_ready : 1; // file system should be writable once this service starts
109 bool log_ready : 1; // syslog should be available once this service starts
111 // Not actually "onstart" commands:
112 bool no_sigterm : 1; // do not send SIGTERM
113 bool runs_on_console : 1; // run "in the foreground"
114 bool starts_on_console : 1; // starts in the foreground
115 bool pass_cs_fd : 1; // pass this service a control socket connection via fd
117 onstart_flags_t() noexcept : rw_ready(false), log_ready(false),
118 no_sigterm(false), runs_on_console(false), starts_on_console(false), pass_cs_fd(false)
123 // Exception while loading a service
124 class service_load_exc
127 std::string serviceName;
128 std::string excDescription;
131 service_load_exc(std::string serviceName, std::string &&desc) noexcept
132 : serviceName(serviceName), excDescription(std::move(desc))
137 class service_not_found : public service_load_exc
140 service_not_found(std::string serviceName) noexcept
141 : service_load_exc(serviceName, "Service description not found.")
146 class service_cyclic_dependency : public service_load_exc
149 service_cyclic_dependency(std::string serviceName) noexcept
150 : service_load_exc(serviceName, "Has cyclic dependency.")
155 class service_description_exc : public service_load_exc
158 service_description_exc(std::string serviceName, std::string &&extraInfo) noexcept
159 : service_load_exc(serviceName, std::move(extraInfo))
164 class service_record;
166 class base_process_service;
168 enum class dependency_type
171 SOFT, // dependency starts in parallel, failure/stop does not affect dependent
172 WAITS_FOR, // as for SOFT, but dependent waits until dependency starts/fails before starting
173 MILESTONE // dependency must start successfully, but once started the dependency becomes soft
176 /* Service dependency record */
179 service_record * from;
183 /* Whether the 'from' service is waiting for the 'to' service to start */
185 /* Whether the 'from' service is holding an acquire on the 'to' service */
188 const dependency_type dep_type;
190 service_dep(service_record * from, service_record * to, dependency_type dep_type_p) noexcept
191 : from(from), to(to), waiting_on(false), holding_acq(false), dep_type(dep_type_p)
194 service_record * get_from() noexcept
199 service_record * get_to() noexcept
205 /* preliminary service dependency information */
209 service_record * const to;
210 dependency_type const dep_type;
212 prelim_dep(service_record *to_p, dependency_type dep_type_p) : to(to_p), dep_type(dep_type_p)
218 class service_child_watcher : public eventloop_t::child_proc_watcher_impl<service_child_watcher>
221 base_process_service * service;
222 dasynq::rearm status_change(eventloop_t &eloop, pid_t child, int status) noexcept;
224 service_child_watcher(base_process_service * sr) noexcept : service(sr) { }
227 // Watcher for the pipe used to receive exec() failure status errno
228 class exec_status_pipe_watcher : public eventloop_t::fd_watcher_impl<exec_status_pipe_watcher>
231 base_process_service * service;
232 dasynq::rearm fd_event(eventloop_t &eloop, int fd, int flags) noexcept;
234 exec_status_pipe_watcher(base_process_service * sr) noexcept : service(sr) { }
237 // service_record: base class for service record containing static information
238 // and current state of each service.
240 // This abstract base class defines the dependency behaviour of services. The actions to actually bring a
241 // service up or down are specified by subclasses in the virtual methods (see especially bring_up() and
247 using string = std::string;
248 using time_val = dasynq::time_val;
252 service_type_t record_type; /* ServiceType::DUMMY, PROCESS, SCRIPTED, INTERNAL */
253 service_state_t service_state = service_state_t::STOPPED; /* service_state_t::STOPPED, STARTING, STARTED, STOPPING */
254 service_state_t desired_state = service_state_t::STOPPED; /* service_state_t::STOPPED / STARTED */
259 onstart_flags_t onstart_flags;
261 string logfile; // log file name, empty string specifies /dev/null
263 bool auto_restart : 1; // whether to restart this (process) if it dies unexpectedly
264 bool smooth_recovery : 1; // whether the service process can restart without bringing down service
266 bool pinned_stopped : 1;
267 bool pinned_started : 1;
268 bool waiting_for_deps : 1; // if STARTING, whether we are waiting for dependencies (inc console) to start
269 // if STOPPING, whether we are waiting for dependents to stop
270 bool waiting_for_console : 1; // waiting for exclusive console access (while STARTING)
271 bool have_console : 1; // whether we have exclusive console access (STARTING/STARTED)
272 bool waiting_for_execstat : 1; // if we are waiting for exec status after fork()
273 bool start_explicit : 1; // whether we are are explicitly required to be started
275 bool prop_require : 1; // require must be propagated
276 bool prop_release : 1; // release must be propagated
277 bool prop_failure : 1; // failure to start must be propagated
281 bool restarting : 1; // re-starting after unexpected termination
283 int required_by = 0; // number of dependents wanting this service to be started
285 // list of dependencies
286 typedef std::list<service_dep> dep_list;
288 // list of dependents
289 typedef std::list<service_dep *> dpt_list;
291 dep_list depends_on; // services this one depends on
292 dpt_list dependents; // services depending on this one
294 service_set *services; // the set this service belongs to
296 std::unordered_set<service_listener *> listeners;
299 bool force_stop; // true if the service must actually stop. This is the
300 // case if for example the process dies; the service,
301 // and all its dependencies, MUST be stopped.
303 int term_signal = -1; // signal to use for process termination
305 string socket_path; // path to the socket for socket-activation service
306 int socket_perms; // socket permissions ("mode")
307 uid_t socket_uid = -1; // socket user id or -1
308 gid_t socket_gid = -1; // socket group id or -1
310 // Data for use by service_set
314 lld_node<service_record> console_queue_node;
316 // Propagation and start/stop queues
317 lls_node<service_record> prop_queue_node;
318 lls_node<service_record> stop_queue_node;
322 // Service has actually stopped (includes having all dependents
323 // reaching STOPPED state).
324 void stopped() noexcept;
326 // Service has successfully started
327 void started() noexcept;
329 // Service failed to start (only called when in STARTING state).
330 // dep_failed: whether failure is recorded due to a dependency failing
331 void failed_to_start(bool dep_failed = false) noexcept;
333 void run_child_proc(const char * const *args, const char *logfile, bool on_console, int wpipefd,
334 int csfd, int socket_fd) noexcept;
336 // A dependency has reached STARTED state
337 void dependency_started() noexcept;
339 void all_deps_started() noexcept;
341 // Start all dependencies, return true if all have started
342 bool start_check_dependencies() noexcept;
344 // Check whether all dependencies have started (i.e. whether we can start now)
345 bool check_deps_started() noexcept;
347 // Whether a STOPPING service can immediately transition to STARTED.
348 bool can_interrupt_stop() noexcept
350 return waiting_for_deps && ! force_stop;
353 // A dependent has reached STOPPED state
354 void dependent_stopped() noexcept;
356 // check if all dependents have stopped
357 bool stop_check_dependents() noexcept;
359 // issue a stop to all dependents, return true if they are all already stopped
360 bool stop_dependents() noexcept;
362 void require() noexcept;
363 void release(bool issue_stop = true) noexcept;
364 void release_dependencies() noexcept;
366 // Check if service is, fundamentally, stopped.
367 bool is_stopped() noexcept
369 return service_state == service_state_t::STOPPED
370 || (service_state == service_state_t::STARTING && waiting_for_deps);
373 void notify_listeners(service_event_t event) noexcept
375 for (auto l : listeners) {
376 l->service_event(this, event);
380 // Queue to run on the console. 'acquired_console()' will be called when the console is available.
381 // Has no effect if the service has already queued for console.
382 void queue_for_console() noexcept;
384 // Release console (console must be currently held by this service)
385 void release_console() noexcept;
387 bool do_auto_restart() noexcept;
389 // Started state reached
390 bool process_started() noexcept;
392 // Called on transition of desired state from stopped to started (or unpinned stop)
393 void do_start() noexcept;
395 // Called on transition of desired state from started to stopped (or unpinned start)
396 void do_stop() noexcept;
398 // Set the service state
399 void set_state(service_state_t new_state) noexcept
401 service_state = new_state;
404 // Virtual functions, to be implemented by service implementations:
406 // Do any post-dependency startup; return false on failure
407 virtual bool bring_up() noexcept;
409 // All dependents have stopped, and this service should proceed to stop.
410 virtual void bring_down() noexcept;
412 // Whether a STARTING service can immediately transition to STOPPED (as opposed to
413 // having to wait for it reach STARTED and then go through STOPPING).
414 virtual bool can_interrupt_start() noexcept
416 return waiting_for_deps;
419 // Whether a STARTING service can transition to its STARTED state, once all
420 // dependencies have started.
421 virtual bool can_proceed_to_start() noexcept
426 // Interrupt startup. Returns true if service start is fully cancelled; returns false if cancel order
427 // issued but service has not yet responded (state will be set to STOPPING).
428 virtual bool interrupt_start() noexcept;
430 // The service is becoming inactive - i.e. it has stopped and will not be immediately restarted. Perform
431 // any appropriate cleanup.
432 virtual void becoming_inactive() noexcept { }
436 service_record(service_set *set, string name)
437 : service_state(service_state_t::STOPPED), desired_state(service_state_t::STOPPED),
438 auto_restart(false), smooth_recovery(false),
439 pinned_stopped(false), pinned_started(false), waiting_for_deps(false),
440 waiting_for_console(false), have_console(false), waiting_for_execstat(false),
441 start_explicit(false), prop_require(false), prop_release(false), prop_failure(false),
442 prop_start(false), prop_stop(false), restarting(false), force_stop(false)
446 record_type = service_type_t::DUMMY;
450 service_record(service_set *set, string name, service_type_t record_type_p,
451 const std::list<prelim_dep> &deplist_p)
452 : service_record(set, name)
456 this->record_type = record_type_p;
458 for (auto & pdep : deplist_p) {
459 auto b = depends_on.emplace(depends_on.end(), this, pdep.to, pdep.dep_type);
460 pdep.to->dependents.push_back(&(*b));
464 virtual ~service_record() noexcept
468 // Get the type of this service record
469 service_type_t get_type() noexcept
474 // begin transition from stopped to started state or vice versa depending on current and desired state
475 void execute_transition() noexcept;
477 void do_propagation() noexcept;
479 // Console is available.
480 void acquired_console() noexcept;
482 // Get the target (aka desired) state.
483 service_state_t get_target_state() noexcept
485 return desired_state;
488 // Set logfile, should be done before service is started
489 void set_log_file(string logfile)
491 this->logfile = logfile;
494 // Set whether this service should automatically restart when it dies
495 void set_auto_restart(bool auto_restart) noexcept
497 this->auto_restart = auto_restart;
500 void set_smooth_recovery(bool smooth_recovery) noexcept
502 this->smooth_recovery = smooth_recovery;
505 // Set "on start" flags (commands)
506 void set_flags(onstart_flags_t flags) noexcept
508 this->onstart_flags = flags;
511 void set_pid_file(string &&pid_file) noexcept
513 this->pid_file = std::move(pid_file);
516 void set_socket_details(string &&socket_path, int socket_perms, uid_t socket_uid, uid_t socket_gid) noexcept
518 this->socket_path = std::move(socket_path);
519 this->socket_perms = socket_perms;
520 this->socket_uid = socket_uid;
521 this->socket_gid = socket_gid;
524 const std::string &get_name() const noexcept { return service_name; }
525 service_state_t get_state() const noexcept { return service_state; }
527 void start(bool activate = true) noexcept; // start the service
528 void stop(bool bring_down = true) noexcept; // stop the service
530 void forced_stop() noexcept; // force-stop this service and all dependents
532 // Pin the service in "started" state (when it reaches the state)
533 void pin_start() noexcept
535 pinned_started = true;
538 // Pin the service in "stopped" state (when it reaches the state)
539 void pin_stop() noexcept
541 pinned_stopped = true;
544 // Remove both "started" and "stopped" pins. If the service is currently pinned
545 // in either state but would naturally be in the opposite state, it will immediately
546 // commence starting/stopping.
547 void unpin() noexcept;
549 bool is_dummy() noexcept
551 return record_type == service_type_t::DUMMY;
554 // Add a listener. A listener must only be added once. May throw std::bad_alloc.
555 void add_listener(service_listener * listener)
557 listeners.insert(listener);
560 // Remove a listener.
561 void remove_listener(service_listener * listener) noexcept
563 listeners.erase(listener);
567 inline auto extract_prop_queue(service_record *sr) -> decltype(sr->prop_queue_node) &
569 return sr->prop_queue_node;
572 inline auto extract_stop_queue(service_record *sr) -> decltype(sr->stop_queue_node) &
574 return sr->stop_queue_node;
577 inline auto extract_console_queue(service_record *sr) -> decltype(sr->console_queue_node) &
579 return sr->console_queue_node;
583 * A service_set, as the name suggests, manages a set of services.
585 * Other than the ability to find services by name, the service set manages various queues.
586 * One is the queue for processes wishing to acquire the console. There is also a set of
587 * processes that want to start, and another set of those that want to stop. These latter
588 * two "queues" (not really queues since their order is not important) are used to prevent too
589 * much recursion and to prevent service states from "bouncing" too rapidly.
591 * A service that wishes to start or stop puts itself on the start/stop queue; a service that
592 * needs to propagate changes to dependent services or dependencies puts itself on the
593 * propagation queue. Any operation that potentially manipulates the queues must be followed
594 * by a "process queues" order (processQueues() method).
596 * Note that processQueues always repeatedly processes both queues until they are empty. The
597 * process is finite because starting a service can never cause services to stop, unless they
598 * fail to start, which should cause them to stop semi-permanently.
604 std::list<service_record *> records;
605 bool restart_enabled; // whether automatic restart is enabled (allowed)
607 shutdown_type_t shutdown_type = shutdown_type_t::CONTINUE; // Shutdown type, if stopping
609 // Services waiting for exclusive access to the console
610 dlist<service_record, extract_console_queue> console_queue;
612 // Propagation and start/stop "queues" - list of services waiting for processing
613 slist<service_record, extract_prop_queue> prop_queue;
614 slist<service_record, extract_stop_queue> stop_queue;
620 restart_enabled = true;
623 virtual ~service_set()
625 for (auto * s : records) {
630 // Start the specified service. The service will be marked active.
631 void start_service(service_record *svc)
637 // Stop the specified service. Its active mark will be cleared.
638 void stop_service(service_record *svc)
644 // Locate an existing service record.
645 service_record *find_service(const std::string &name) noexcept;
647 // Load a service description, and dependencies, if there is no existing
648 // record for the given name.
650 // ServiceLoadException (or subclass) on problem with service description
651 // std::bad_alloc on out-of-memory condition
652 virtual service_record *load_service(const char *name)
654 auto r = find_service(name);
656 throw service_not_found(name);
661 // Start the service with the given name. The named service will begin
662 // transition to the 'started' state.
664 // Throws a ServiceLoadException (or subclass) if the service description
665 // cannot be loaded or is invalid;
666 // Throws std::bad_alloc if out of memory.
667 void start_service(const char *name)
670 service_record *record = load_service(name);
671 service_set::start_service(record);
674 void add_service(service_record *svc)
676 records.push_back(svc);
679 void remove_service(service_record *svc)
681 std::remove(records.begin(), records.end(), svc);
684 // Get the list of all loaded services.
685 const std::list<service_record *> &list_services() noexcept
690 // Stop the service with the given name. The named service will begin
691 // transition to the 'stopped' state.
692 void stop_service(const std::string &name) noexcept;
694 // Add a service record to the state propagation queue. The service record will have its
695 // do_propagation() method called when the queue is processed.
696 void add_prop_queue(service_record *service) noexcept
698 if (! prop_queue.is_queued(service)) {
699 prop_queue.insert(service);
703 // Add a service record to the stop queue. The service record will have its
704 // execute_transition() method called when the queue is processed.
705 void add_transition_queue(service_record *service) noexcept
707 if (! stop_queue.is_queued(service)) {
708 stop_queue.insert(service);
712 // Process state propagation and start/stop queues, until they are empty.
713 void process_queues() noexcept
715 while (! stop_queue.is_empty() || ! prop_queue.is_empty()) {
716 while (! prop_queue.is_empty()) {
717 auto next = prop_queue.pop_front();
718 next->do_propagation();
720 while (! stop_queue.is_empty()) {
721 auto next = stop_queue.pop_front();
722 next->execute_transition();
727 // Set the console queue tail (returns previous tail)
728 void append_console_queue(service_record * newTail) noexcept
730 bool was_empty = console_queue.is_empty();
731 console_queue.append(newTail);
733 enable_console_log(false);
737 // Pull and dispatch a waiter from the console queue
738 void pull_console_queue() noexcept
740 if (console_queue.is_empty()) {
741 enable_console_log(true);
744 service_record * front = console_queue.pop_front();
745 front->acquired_console();
749 void unqueue_console(service_record * service) noexcept
751 if (console_queue.is_queued(service)) {
752 console_queue.unlink(service);
756 // Check if console queue is empty (possibly due to console already having
757 // been assigned to the only queueing service)
758 bool is_console_queue_empty() noexcept
760 return console_queue.is_empty();
763 // Check whether a service is queued for the console
764 bool is_queued_for_console(service_record * service) noexcept
766 return console_queue.is_queued(service);
769 // Notification from service that it is active (state != STOPPED)
770 // Only to be called on the transition from inactive to active.
771 void service_active(service_record *) noexcept;
773 // Notification from service that it is inactive (STOPPED)
774 // Only to be called on the transition from active to inactive.
775 void service_inactive(service_record *) noexcept;
777 // Find out how many services are active (starting, running or stopping,
779 int count_active_services() noexcept
781 return active_services;
784 void stop_all_services(shutdown_type_t type = shutdown_type_t::HALT) noexcept
786 restart_enabled = false;
787 shutdown_type = type;
788 for (std::list<service_record *>::iterator i = records.begin(); i != records.end(); ++i) {
795 void set_auto_restart(bool restart) noexcept
797 restart_enabled = restart;
800 bool get_auto_restart() noexcept
802 return restart_enabled;
805 shutdown_type_t get_shutdown_type() noexcept
807 return shutdown_type;
811 class dirload_service_set : public service_set
813 const char *service_dir; // directory containing service descriptions
816 dirload_service_set(const char *service_dir_p) : service_set(), service_dir(service_dir_p)
820 service_record *load_service(const char *name) override;